Mission requirements typically dictate the configurations of aircraft. For example, aircraft with long-range mission requirements are typically configured to carry large quantities of fuel to increase their range between fuel stops. In addition, such aircraft are typically configured with relatively large wings to enable them to take off and land on conventional airport runways with heavy fuel loads. In contrast, aircraft with short-range mission requirements do not need to carry large quantities of fuel. Consequently, they typically require less wing area and have lower operating empty weights than long-range aircraft having comparable passenger capacities. As a result, using a long-range aircraft for a short flight can be very inefficient because the unnecessarily high empty weight of the long-range aircraft can result in poor fuel economy.
Accordingly, it would be advantageous for an aircraft manufacturer to be able to offer a wide range of aircraft configurations, with each configuration being tailored to a particular mission. In this way, customers desiring long-range aircraft could order models having relatively large fuel capacities and large wings, and customers desiring short-range aircraft could order models having relatively small fuel capacities and small wings. In practice, however, the cost associated with designing, manufacturing, and certifying a new aircraft is substantial. As a result, many aircraft manufacturers offer only a limited range of models that, not surprisingly, represent a compromise of disparate mission requirements.
One way that aircraft manufacturers try to minimize the high cost associated with developing new aircraft is to develop “derivative” aircraft. Derivative aircraft are “new” aircraft designs derived from existing aircraft designs. By utilizing many of the components and features from the existing aircraft designs, derivative aircraft can greatly reduce the cost of designing, manufacturing, and certifying a new aircraft configuration.
FIGS. 1A-C are top views of three derivative aircraft wings 101a-c, respectively, in accordance with the prior art. Each of the derivative aircraft wings 101a-c provides more wing area than an existing wing 102 from which it was derived. For example, the derivative aircraft wing 101a shown in FIG. 1A includes the existing wing 102 and a wing-root insert 104a extending between the existing wing 102 and a fuselage 110. The existing wing 102 includes an engine pod 142 and landing gear assembly 108 that are, accordingly, moved away from the fuselage 110 by the wing insert 104a. The derivative aircraft wing 101b shown in FIG. 1B includes a chordwise wing insert 104b extending between forward and aft portions of the existing wing 102. The derivative aircraft wing 101c shown in FIG. 1C includes a wing-tip extension 104c extending outward from the existing wing 102.
Each of the derivative aircraft wings 101a-c has shortcomings. For example, the wing-root insert 104a shown in FIG. 1A shifts the landing gear assembly 108, the engine pod 142, and other wing systems (e.g., leading edge slats, trailing edge flaps, and spoilers) away from the fuselage 110, thus necessitating, at a minimum, lengthening of the fuel, hydraulic, and electrical lines that extend to these systems from the fuselage 110. In addition, shifting the engine pod 142 further outboard can also require a redesign of the rudder of the baseline aircraft (not shown) to compensate for increased yaw forces resulting from an “engine out” design condition.
The chordwise insert 104b shown in FIG. 1B also has a number of shortcomings. For example, the addition of the chordwise insert 104b may require relofting the entire wing to restore the original airfoil shape of the existing wing 102 to the cross-section. In addition, the existing wing 102 must be reworked along the entire span to integrate the chordwise insert 104b with the existing structure.
The wing-tip extension 104c shown in FIG. 1C also has shortcomings. Although this may be the simplest approach to increasing wing area, the wing tip extension 104c unfavorably shifts the center of pressure on the wing outboard, thereby increasing the bending loads on the existing wing 102. As a result, adding the wing-tip extension 104c can require structurally reinforcing the existing wing 102, especially at the attachment to the fuselage 110. A further shortcoming associated with the wing-tip extension 104c is that structural reinforcement is often required at the tip of the existing wing 102 to carry the loads introduced from the wing-tip extension 104c. Still further, the wing-tip extension 104c typically does not provide a substantial increase in wing area or fuel volume.